/**
 * Author: frogcherry
 * Email: frogcherry@gmail.com
 * created: 2011.09.17
 */

circle = exports;

var PI = Math.PI; 
circle.PI = Math.PI;
function pow(x){
    return x*x;
}
circle.area = function (r) { 
    return PI * pow(r); 
}; 
circle.circumference = function (r) { 
    return 2 * PI * r; 
};
